Sarah Galvis1, Josh Arnold2, Erin Mannen1, Benjamin Wong1, Hadley Sis1, Eileen Cadel1, John Anderson3, Dennis Anderson4, Paul Arnold5, Elizabeth Friis6. 1. University of Kansas, 1450 Jayhawk Blvd Mechanical Engineering and Bioengineering, 1530 W. 15th St., 3138 Learned Hall, Lawrence, KS 66045, USA. 2. Tufts University, 419 Boston Ave, Medford, MA 02155, USA. 3. Children's Mercy Hospital, 2401 Gillham Rd, Kansas City, MO 64108, USA. 4. Harvard Medical School, 25 Shattuck St, Boston, MA 02115, USA. 5. University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, USA. 6. University of Kansas, 1450 Jayhawk Blvd Mechanical Engineering and Bioengineering, 1530 W. 15th St., 3138 Learned Hall, Lawrence, KS 66045, USA. Electronic address: lfriis@ku.edu.
Abstract
BACKGROUND: Distraction-type rods mechanically stabilize the thorax and improve lung growth and function by applying distraction forces at the rib, spine, pelvis, or a combination of locations. However, the amount of stability the rods provide and the amount the thorax needs is unknown. METHODS: Five freshly frozen and thawed cadaveric thoracic spine specimens were tested for lateral bending, flexion/extension, and axial rotation in displacement control (1°/sec) to a load limit of ±5 Nm for five cycles after which a growth-friendly unilateral rod was placed in a simulated rib-to-lumbar attachment along the right side. The specimens were tested again in the same modes of bending. From the seven Optotrak Orthopedic Research Pin markers (Northern Digital Inc., Waterloo, Ontario, Canada) inserted into the top potting to denote T1, and the right pedicles at T2, T4, T5, T8, T9, and T11 and the Standard Needle Tip Pressure Transducers (Gaeltech, Isle of Skye, Scotland) inserted into the T4/T5 and T8/T9 discs, motion, stiffness, and pressure data were calculated. Parameters from the third cycle of the intact case and the construct case were compared using two-tailed paired t tests with 0.05 as the level of significance. RESULTS: With the construct attached, the T1-T4 segment showed a 30% increase in neutral zone stiffness during extension (p = .001); the T8-T12 segment experienced a 63% reduction in the in-plane range of motion during flexion (p = .04); and the T8/T9 spinal motion unit had a significant decrease of 24% in elastic zone stiffness during left axial rotation (p = .04). CONCLUSIONS: It is clear the device as tested here does not produce large biomechanical changes, but the balance between providing desired changes while preventing complications remains difficult.
BACKGROUND: Distraction-type rods mechanically stabilize the thorax and improve lung growth and function by applying distraction forces at the rib, spine, pelvis, or a combination of locations. However, the amount of stability the rods provide and the amount the thorax needs is unknown. METHODS: Five freshly frozen and thawed cadaveric thoracic spine specimens were tested for lateral bending, flexion/extension, and axial rotation in displacement control (1°/sec) to a load limit of ±5 Nm for five cycles after which a growth-friendly unilateral rod was placed in a simulated rib-to-lumbar attachment along the right side. The specimens were tested again in the same modes of bending. From the seven Optotrak Orthopedic Research Pin markers (Northern Digital Inc., Waterloo, Ontario, Canada) inserted into the top potting to denote T1, and the right pedicles at T2, T4, T5, T8, T9, and T11 and the Standard Needle Tip Pressure Transducers (Gaeltech, Isle of Skye, Scotland) inserted into the T4/T5 and T8/T9 discs, motion, stiffness, and pressure data were calculated. Parameters from the third cycle of the intact case and the construct case were compared using two-tailed paired t tests with 0.05 as the level of significance. RESULTS: With the construct attached, the T1-T4 segment showed a 30% increase in neutral zone stiffness during extension (p = .001); the T8-T12 segment experienced a 63% reduction in the in-plane range of motion during flexion (p = .04); and the T8/T9 spinal motion unit had a significant decrease of 24% in elastic zone stiffness during left axial rotation (p = .04). CONCLUSIONS: It is clear the device as tested here does not produce large biomechanical changes, but the balance between providing desired changes while preventing complications remains difficult.
Authors: Robert M Campbell; Melvin D Smith; Thomas C Mayes; John A Mangos; Donna B Willey-Courand; Nusret Kose; Ricardo F Pinero; Marden E Alder; Hoa L Duong; Jennifer L Surber Journal: J Bone Joint Surg Am Date: 2003-03 Impact factor: 5.284
Authors: Chandan G Reddy; Michael Magnetta; Nader S Dahdaleh; Matthew Demmer; Kingsley Abode Iyamah; Tae-Hong Lim; James C Torner; Patrick W Hitchon Journal: Neurosurgery Date: 2012-04 Impact factor: 4.654
Authors: Joshua D Auerbach; Baron S Lonner; Thomas J Errico; Andrew Freeman; Derek Goerke; Brian P Beaubien Journal: Spine (Phila Pa 1976) Date: 2012-03-01 Impact factor: 3.468
Authors: J Cabello; J M Cavanilles-Walker; M Iborra; M T Ubierna; A Covaro; J Roca Journal: Arch Orthop Trauma Surg Date: 2013-02-01 Impact factor: 3.067
Authors: Dennis E Anderson; Erin M Mannen; Hadley L Sis; Benjamin M Wong; Eileen S Cadel; Elizabeth A Friis; Mary L Bouxsein Journal: J Biomech Date: 2016-02-26 Impact factor: 2.712
Authors: Dennis E Anderson; Erin M Mannen; Rebecca Tromp; Benjamin M Wong; Hadley L Sis; Eileen S Cadel; Elizabeth A Friis; Mary L Bouxsein Journal: J Biomech Date: 2017-10-12 Impact factor: 2.712